The underlying mechanisms of uveitis remain poorly understood. However, a recently identified gene called Nod2, provides important insight into the genetics involved in the pathogenesis of uveitis. Mutations in Nod2 result in Blau syndrome and predispose to Crohn's disease, both of which are autoimmune diseases characterized by uveitis. Thus, this proposal seeks to investigate Nod2 expression in the eye and examine how disease-associated mutations in Nod2 alter cellular inflammatory functions. Although Nod2 was orginally thought to be primarily expressed in monocytes, the preliminary data presented suggest that Nod2 is more widespread and appears to be located in the eye, the main tissue affected by Blau syndrome. The focus of Aim1 is to demonstrate the Nod2 is located in the eye. The cellular distribution of Nod2 will be examined by immunohistochemistry in human eye explants. Nod2 regulation will be examined in cultured endothelilal cells from human iris/choroid tissue, and we will test whether endothelial cultures functionally respond to treatment with Nod2-ligand (MDP). In Aim2 we will use transfected cell lines to investigate how abnormal Nod2 (due to Blau-mutation (R334Q) or Crohn's-mutation (L1007fs)) alters NF-kB activity and cytokine production in response to MDP-treatment or TLR-responses in the setting of MDP-priming. Together, these studies will provide valuable new information on how Nod2 is involved in autoimmunity and the pathogeneis of uveitis.